friction heat

Tian jade formation

Lantian jade belongs to metamorphic rock formed by later.

In the Imperial Palace Museum collection of the Han Dynasty jade and Xi'an of Emperor Wu of the Western Han Dynasty unearthed near the large" jade shop first", after identification, they are a kind of serpentinized marble, also known as the Lantian jade, is the origin of Shaanxi Lantian County names.

Since seventy time, geological workers in Lantian County Lantian jade. It is a kind of serpentinized marble. White marble was full of green grass with slippery sense of serpentine, Geological properties
when containing other impurities, also can appear red, yellow, black and other colors. Serpentinized marble of Lantian jade is composed of limestone, carbonate rock, dolomite by water solution, recrystallize into. During metamorphism of magnesian minerals ( such as dolomite ) can be turned into a serpentine.

Metamorphism

Metamorphism is defined by Lyell ( 1833) systematically presented. Metamorphism is defined with the crustal formation and development are closely related to a geological process, is in the earth's crust formation and evolution process of the earth, due to the change of internal forces, so that the existing crustal rocks in maintaining the basic state conditions, the original rock of general chemistry remained unchanged, the formation of new mineral composition and structure.

Metamorphism and magmatism sedimentation, there is certain difference and relation. Metamorphism and magmatism are relatively easy to distinguish between,contact metamorphism
the line between them is molten, and deposited into the rock action is an important symbol of mineral assemblages changes, generally with laumontite began to appear as a symbol. Control and effect of metamorphic factors of temperature and pressure.

Temperature effect

Temperature control and influence of metamorphism is one of the important factors. The majority of metamorphism is decreased with increasing temperature and the. The original rock temperatures in some mineral recrystallization, more important is to be able to make a variety of original components reconfigured into new mineral.

To determine the metamorphism occurred in the temperature range, both the initial and final temperature. Does not include the effects of weathering and metamorphism of sedimentary rocks into rocks.

But in the laumontite,jewelry factory glaucophane, lawsonite, paragonite, leaf Lashi and other metamorphic minerals in the first appeared, as the beginning of metamorphism. These minerals occur when the temperature range is in 150 degrees - 250 degrees. This is the metamorphism occurred starting temperature. Because metamorphism does not include raw rock mass of molten rock, end temperature is the original large-scale melting temperature, now identified as of 650 degrees - 100 degrees.

The second is about the causes of temperature changes, mainly has the following several kinds of factors:

Geothermal: rock with burial depth increases, while the temperature gradually increased, but its magnitude is generally small, according to the regional geological environment is different, from every kilometer ten degrees to more than 100 degrees, however its space scope. Geological workers called the change for geothermal increment rate or temperature gradient.

Radioactive element decay heat released: characterized by gross is big, uneven, sometimes very considerable.

Magma activities bring the heat: its strength and magmatic activity related to the scale, sometimes the scope is very small, only contact zone, which is called the contact metamorphism, and sometimes may also affect a region. Stress under the action of friction heat: the more local, such as fault zone.